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Question
The mean weight of 120 students of a school is 52.75 kg. If the mean weight of 50 of them is 51 kg,
find the mean weight of the remaining students.
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Solution
Mean weight of 120 students = 52.75 kg
⇒ Sum of the weight of 120 students = 120 x 52.75 = 6330 kg
Mean weight of 50 students = 51 kg
⇒ Sum of the weight of 50 students = 50 x 51 = 2550 kg
⇒ Sum of the weight of remaining ( 120 - 50 ) = 70 students
= Sum of the weight of 120 students - Sum of the weight of 50 students
= ( 6330 - 2550 ) kg
= 3780 kg
⇒ Mean weight of remaining 70 students = `3780/70` = 54 kg.
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